Various types of rotating electric machines such as electric motors that cool magnets or coil ends of a stator with a cooling oil or the like have been conventionally proposed. For example, an electric motor described in Japanese Patent Laying-Open No. 2006-006091 includes a rotor having permanent magnets, a rotor with coils wound therearound, and an ejection hole for ejecting a coolant toward the permanent magnets.
In this rotating electric machine, the coolant is ejected to coil ends after magnetic impurities contained in the coolant are adsorbed to the magnets, thereby preventing an insulation coating at the coil ends from being damaged.
A rotating electric machine described in Japanese Patent Laying-Open No. 2005-006429 includes a stator with a plurality of slots formed therein and a rotor arranged rotatably in a hollow portion of this stator. An insulation paper is disposed in the slots, around which coils are wound. This rotating electric machine includes a cooling oil passage supplying a coolant to end faces of the rotor, and inclined portions guiding the coolant to the coil ends located above the insulation paper.
In an electric motor described in Japanese Patent Laying-Open No. 2003-169448, a lubricating oil supplied to bearing components of a rotor shaft passes along a lubricant path defined in the rotor and is ejected toward coil ends of a stator, thereby cooling the coil ends.
An electric motor described in Japanese Patent Laying-Open No. 2001-016826 includes a rotor shaft having a hollow portion and a rotor with an oil passage formed therein communicating with the hollow portion. The oil passage formed in the rotor communicates with an oil storing space formed at an axial end face of the rotor. The oil storing space has an ejection hole narrower than the oil storing space. Atomized lubricating oil is supplied into the stator to cool the electric motor.
However, in the rotating electric machines configured as described above, an insulation coating at the coil ends of the stator is stripped of due to spraying of the coolant from the rotor toward the coil ends. In order to suppress thermal demagnetization of the magnets, the permanent magnets and an iron core of the rotor need to be cooled.